Transcript GSM Security An overview

GSM and 3G Security
Emmanuel Gadaix
Asia April 2001
Agenda
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Brief introduction to GSM networking
Cryptography issues
Terminal and SIM
SS7 Signalling
GSM Data
Value-Added Services
Third generation
Lawful interception
GSM: Introduction
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GSM is the most widely used cellular standard
Over 600 million users, mostly in Europe and Asia
Limited coverage and support in USA
Based on TDMA radio access and PCM trunking
Use SS7 signalling with mobile-specific extensions
Provides authentication and encryption capabilities
Today’s networks are 2G evolving to 2.5G
Third generation (3G) and future (4G)
Low-tech Fraud
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Call forwarding to premium rate numbers
Bogus registration details
Roaming fraud
Terminal theft
Multiple forwarding, conference calls
Countermeasures for low-tech fraud
Fraud Management systems look for:
– Multiple calls at the same time,
– Large variations in revenue being paid to other parties,
– Large variations in the duration of calls, such as very short or
long calls,
– Changes in customer usage, perhaps indicating that a mobile
has been stolen or is being abused,
– Monitor the usage of a customer closely during a 'probationary
period'
Problems with GSM security
• Only provides access security – communications and
signalling traffic in the fixed network are not protected.
• Does not address active attacks, whereby some network
elements (e.g. BTS: Base Station)
• Only as secure as the fixed networks to which they connect
• Lawful interception only considered as an after-thought
• Terminal identity cannot be trusted
• Difficult to upgrade the cryptographic mechanisms
• Lack of user visibility (e.g. doesn’t know if encrypted or not)
Attacks on GSM networks
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Eavesdropping. This is the capability that the intruder eavesdrops
signalling and data connections associated with other users. The
required equipment is a modified MS.
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Impersonation of a user. This is the capability whereby the
intruder sends signalling and/or user data to the network, in an
attempt to make the network believe they originate from the target
user. The required equipment is again a modified MS.
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Impersonation of the network. This is the capability whereby the
intruder sends signalling and/or user data to the target user, in an
attempt to make the target user believe they originate from a
genuine network. The required equipment is modified BTS.
Attacks on GSM networks
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Man-in-the-middle. This is the capability whereby the intruder puts
itself in between the target user and a genuine network and has the
ability to eavesdrop, modify, delete, re-order, replay, and spoof
signalling and user data messages exchanged between the two
parties. The required equipment is modified BTS in conjunction
with a modified MS.
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Compromising authentication vectors in the network. The
intruder possesses a compromised authentication vector, which
may include challenge/response pairs, cipher keys and integrity
keys. This data may have been obtained by compromising network
nodes or by intercepting signalling messages on network links.
De-registration spoofing
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An attack that requires a modified MS and exploits the weakness
that the network cannot authenticate the messages it receives over
the radio interface.
The intruder spoofs a de-registration request (IMSI detach) to the
network.
The network de-registers the user from the visited location area
and instructs the HLR to do the same. The user is subsequently
unreachable for mobile terminated services.
3G: Integrity protection of critical signalling messages protects
against this attack. More specifically, data authentication and replay
inhibition of the de-registration request allows the serving network
to verify that the de-registration request is legitimate.
Location update spoofing
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An attack that requires a modified MS and exploits the weakness
that the network cannot authenticate the messages it receives over
the radio interface.
The user spoofs a location update request in a different location
area from the one in which the user is roaming.
The network registers in the new location area and the target user
will be paged in that new area.
The user is subsequently unreachable for mobile terminated
services.
3G: Integrity protection of critical signalling messages protects
against this attack. More specifically, data authentication and replay
inhibition of the location update request allows the serving network
to verify that the location update request is legitimate.
Camping on a false BTS
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An attack that requires a modified BTS and exploits the weakness
that a user can be enticed to camp on a false base station.
Once the target user camps on the radio channels of a false base
station, the target user is out of reach of the paging signals of the
serving network in which he is registered.
3G: The security architecture does not counteract this attack.
However, the denial of service in this case only persists for as long
as the attacker is active unlike the above attacks which persist
beyond the moment where intervention by the attacker stops.
These attacks are comparable to radio jamming which is very
difficult to counteract effectively in any radio system.
Camping on false BTS/MS
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An attack that requires a modified BTS/MS and exploits the
weakness that a user can be enticed to camp on a false base
station.
A false BTS/MS can act as a repeater for some time and can relay
some requests in between the network and the target user, but
subsequently modify or ignore certain service requests and/or
paging messages related to the target user.
3G: The security architecture does not prevent a false BTS/MS
relaying messages between the network and the target user,
neither does it prevent the false BTS/MS ignoring certain service
requests and/or paging requests.
Integrity protection of critical message may however help to
prevent some denial of service attacks, which are induced by
modifying certain messages.
Passive Identity Caching
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A passive attack that requires a modified MS and exploits the
weakness that the network may sometimes request the user to
send its identity in cleartext.
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3G: The identity confidentiality mechanism counteracts this attack.
The use of temporary identities allocated by the serving network
makes passive eavesdropping inefficient since the user must wait
for a new registration or a mismatch in the serving network
database before he can capture the user’s permanent identity in
plaintext.
The inefficiency of this attack given the likely rewards to the
attacker would make this scenario unlikely.
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Active Identity Caching
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An active attack that requires a modified BTS and exploits the
weakness that the network may request the MS to send its
permanent user identity in cleartext.
An intruder entices the target user to camp on its false BTS and
subsequently requests the target user to send its permanent user
identity in cleartext perhaps by forcing a new registration or by
claiming a temporary identity mismatch due to database failure.
3G: The identity confidentiality mechanism counteracts this attack
by using an encryption key shared by a group of users to protect
the user identity in the event of new registrations or temporary
identity database failure in the serving network.
Suppressing encryption between
the target user and the intruder
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An attack that requires a modified BTS and that exploits the
weakness that the MS cannot authenticate messages received
over the radio interface.
The target user is enticed to camp on the false BTS. When the
intruder or the target user initiates a service, the intruder does not
enable encryption by spoofing the cipher mode command.
The intruder maintains the call as long as it is required or as long
as his attack remains undetected.
3G: A mandatory cipher mode command with message
authentication and replay inhibition allows the mobile to verify that
encryption has not been suppressed by an attacker.
Suppressing encryption between
target user and the true network
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An attack that requires a modified BTS/MS and that exploits the
weakness that the network cannot authenticate messages received
over the radio interface.
The target user is enticed to camp on the false BTS/MS. When a
call is set-up the false BTS/MS modifies the ciphering capabilities
of the MS to make it appear to the network that a genuine
incompatibility exists between the network and the mobile station.
The network may then decide to establish an un-enciphered
connection. After the decision not to cipher has been taken, the
intruder cuts the connection with the network and impersonates the
network to the target user.
3G: A mobile station classmark with message authentication and
replay inhibition allows the network to verify that encryption has not
been suppressed by an attacker.
Compromised cipher key
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An attack that requires a modified BTS and the possession by the
intruder of a compromised authentication vector and thus exploits
the weakness that the user has no control upon the cipher key.
The target user is enticed to camp on the false BTS/MS. When a
call is set-up the false BTS/MS forces the use of a compromised
cipher key on the mobile user.
3G: The presence of a sequence number in the challenge allows
the USIM to verify the freshness of the cipher key to help guard
against forced re-use of a compromised authentication vector.
However, the architecture does not protect against force use of
compromised authentication vectors which have not yet been used
to authenticate the USIM.
Thus, the network is still vulnerable to attacks using compromised
authentication vectors which have been intercepted between
generation in the authentication center and use or destruction in
the serving network.
Eavesdropping on user data
by suppressing encryption
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An attack that requires a modified BTS/MS and that exploits the
weakness that the MS cannot authenticate messages received
over the radio interface.
The target user is enticed to camp on the false BTS. When the
target user or the intruder initiates a call the network does not
enable encryption by spoofing the cipher mode command.
The attacker however sets up his own connection with the genuine
network using his own subscription. The attacker may then
subsequently eavesdrop on the transmitted user data.
3G: A mandatory cipher mode command with message
authentication and replay inhibition allows the mobile to verify that
encryption has not been suppressed by an attacker.
Suppression of encryption between
target user and true network
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The target user is enticed to camp on the false BTS/MS. When the
target user or the genuine network sets up a connection, the false
BTS/MS modifies the ciphering capabilities of the MS to make it
appear to the network that a genuine incompatibility exists between
the network and the mobile station.
The network may then decide to establish an un-enciphered
connection. After the decision not to cipher has been taken, the
intruder may eavesdrop on the user data.
3G: Message authentication and replay inhibition of the mobile’s
ciphering capabilities allows the network to verify that encryption
has not been suppressed by an attacker.
Eavesdropping on user data by forcing
the use of a compromised cipher key
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An attack that requires a modified BTS/MS and the possession by
the intruder of a compromised authentication vector and thus
exploits the weakness that the user has no control the cipher key.
The target user is enticed to camp on the false BTS/MS. When the
target user or the intruder set-up a service, the false BTS/MS
forces the use of a compromised cipher key on the mobile user
while it builds up a connection with the genuine network using its
own subscription.
3G: The presence of a sequence number in the challenge allows
the USIM to verify the freshness of the cipher key to help guard
against forced re-use of a compromised authentication vector.
However, the architecture does not protect against force use of
compromised authentication vectors, which have not yet been used
to authenticate the USIM. Thus, the network is still vulnerable to
attacks using compromised authentication vectors.
User impersonation with compromised
authentication vector
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An attack that requires a modified MS and the possession by the
intruder of a compromised authentication vector which is intended
to be used by the network to authenticate a legitimate user.
The intruder uses that data to impersonate the target user towards
the network and the other party.
3G: The presence of a sequence number in the challenge means
that authentication vectors cannot be re-used to authenticate
USIMs. This helps to reduce the opportunity of using a
compromised authentication vector to impersonate the target user.
However, the network is still vulnerable to attacks using
compromised authentication vectors.
User impersonation through eavesdropped
authentication response
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An attack that requires a modified MS and exploits the weakness
that an authentication vector may be used several times.
The intruder eavesdrops on the authentication response sent by
the user and uses that when the same challenge is sent later on.
Subsequently, ciphering has to be avoided by any of the
mechanisms described above. The intruder uses the eavesdropped
response data to impersonate the target user towards the network
and the other party
3G: The presence of a sequence number in the challenge means
that authentication vectors cannot be re-used to authenticate
USIMs
Hijacking outgoing calls in networks
with encryption disabled
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This attack requires a modified BTS/MS. While the target user camps on
the false base station, the intruder pages the target user for an incoming
call.
The user then initiates the call set-up procedure, which the intruder allows
to occur between the serving network and the target user, modifying the
signalling elements such that for the serving network it appears as if the
target user wants to set-up a mobile originated call.
The network does not enable encryption. After authentication the intruder
cuts the connection with the target user, and subsequently uses the
connection with the network to make fraudulent calls on the target user’s
subscription.
3G: Integrity protection of critical signalling messages protects against this
attack. More specifically, data authentication and replay inhibition of the
connection set-up request allows the serving network to verify that the
request is legitimate.
In addition, periodic integrity protected messages during a connection
helps protect against hijacking of un-enciphered connections after the initial
connection establishment.
Hijacking outgoing calls in networks
with encryption enabled
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This attack requires a modified BTS/MS. In addition to the previous
attack this time the intruder has to attempt to suppress encryption
by modification of the message in which the MS informs the
network of its ciphering capabilities.
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3G: Integrity protection of critical signalling messages protects
against this attack. More specifically, data authentication and replay
inhibition of the MS station classmark and the connection set-up
request helps prevent suppression of encryption and allows the
serving network to verify that the request is legitimate.
Hijacking incoming calls in networks
with encryption disabled
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This attack requires a modified BTS/MS. While the target user camps on
the false base station, an associate of the intruder makes a call to the
target user’s number.
The intruder acts as a relay between the network and the target user until
authentication and call set-up has been performed between target user and
serving network. The network does not enable encryption.
After authentication and call set-up the intruder releases the target user,
and subsequently uses the connection to answer the call made by his
associate. The target user will have to pay for the roaming leg.
3G: Integrity protection of critical signalling messages protects against this
attack. More specifically, data authentication and replay inhibition of the
connection accept message allows the serving network to verify that the
request is legitimate.
In addition, periodic integrity protected messages during a connection
helps protect against hijacking of un-enciphered connections after the initial
connection establishment.
Hijacking incoming calls in networks
with encryption enabled
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This attack requires a modified BTS/MS. In addition to the previous
attack this time the intruder has to suppress encryption.
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3G: Integrity protection of critical signalling messages protects
against this attack. More specifically, data authentication and replay
inhibition of the MS station classmark and the connection accept
message helps prevent suppression of encryption and allows the
serving network to verify that the connection accept is legitimate.
Cryptography
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GSM consortium decide to go “security through obscurity”
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A3/A5/A8 algorithms eventually leaked
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Cryptanalysis attacks against A5
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Attacks on COMP-128 algorithm
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Evolution of security model
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Key recovery allowing SIM cloning
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Over-the-air interception using fake BTS
Fake BTS
• IMSI catcher by Law Enforcement
• Intercept mobile originated calls
• Can be used for over-the-air cloning
Terminology
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AKA
AN
HE
SN
USIM
Authentication and Key Agreement
Access Network
Home Environment
Serving Network
User Services Identity Module
Terminal and SIM
• SIM = Subscriber Identity Module
• Terminal = subscriber’s handset
• The SIM is a smartcard device containing cryptographic
secrets
• Hardware to copy SIM
• Client-side security doesn’t work
• Terminal is also a radio network monitoring tool, a signallingaware RX/TX, a computer with lots of capabilities
• Applications can run on the SIM
MExE: Mobile Execution Environment
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The ability to remotely modify remote and run code on a mobile
clearly introduces a security risk.
In the case of MExE it is up to the user to determine if a possible
security risk is introduced, and stop the action from taking place.
It is to be expected that a smart attacker will be able to introduce
code that will fool a user into setting up services or connection that
will compromise them or result them in losing money
GSM Data
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Initially designed to carry voice traffic
Data connections initially 9600 bps
No need for modems as there is a digital path from MS to MSC
Enhanced rates up to 14.4 kbps
GPRS provides speeds up to 150 kbps
UMTS (3G) promises permanent connections with up to 2 Mbps
transfer rate
Signalling
• GSM uses SS7 signalling for call control, mobility
management, short messages and value-added services
• MTP1-3: Message Transfer Part
• SCCP: Signalling Connection Control Part
• TCAP: Transaction Capabilities Application Part
• MAP: Mobile Application Part
• BSSAP: Base Station Subsystem Application Part
• INAP: Intelligent Network Application Part
• CAMEL: Customized Application for Mobile Enhanced Logic
Signalling Security
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Mobile networks primarily use Signaling System no. 7 (SS7) for
communication between networks for such activities as
authentication, location update, and supplementary services and
call control. The messages unique to mobile communications are
MAP messages.
The security of the global SS7 network as a transport system for
signaling messages e.g. authentication and supplementary
services such as call forwarding is open to major compromise.
The problem with the current SS7 system is that messages can be
altered, injected or deleted into the global SS7 networks in an
uncontrolled manner
SS7: opening up to the world
• In the past, SS7 traffic was passed between major PTO’s
covered under treaty organization and the number of
operators was relatively small and the risk of compromise
was low.
• Networks are getting smaller and more numerous.
Opportunities for unintentional mishaps will increase, as will
the opportunities for hackers and other abusers of networks.
• With the increase in different types of operators and the
increase in the number of interconnection circuits there is an
ever-growing loss of control of security of the signaling
networks.
SS7: waiting for disaster
• There is also exponential growth in the use of
interconnection between the telecommunication networks
and the Internet .
• The IT community now has many protocol converters for
conversion of SS7 data to IP, primarily for the transportation
of voice and data over the IP networks. In addition new
services such as those based on IN will lead to a growing
use of the SS7 network for general data transfers.
• There have been a number of incidents from accidental
action, which have damaged a network. To date, there have
been very few deliberate actions
SS7: evolution
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The availability of cheap PC based equipment that can be used to
access networks and the ready availability of access gateways on
the Internet will lead to compromise of SS7 signaling and this will
effect mobile operators.
The risk of attack has been recognized in the USA at the highest
level of the President’s office indicating concern on SS7. It is
understood that the T1, an American group is seriously considering
the issue.
For the network operator there is some policing of incoming
signaling on most switches already, but this is dependent on the
make of switch as well as on the way the switch is configured by
operators.
Some engineering equipment is not substantially different from
other advanced protocol analyzers in terms of its fraud potential,
but is more intelligent and can be programmed more easily
SS7: what to do
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Operators ensure that signaling screening of SS7 incoming
messages takes place at the entry points to their networks and that
operations and maintenance systems alert against unusual SS7
messages.
There are a number of messages that can have a significant effect
on the operation of the network and inappropriate messages
should be controlled at entry point.
Network operators network security engineers should on a regular
basis carry out monitoring of signaling links for these inappropriate
messages.
In signing agreements with roaming partners and carrying out
roaming testing, review of messages and also to seek appropriate
confirmation that network operators are also screening incoming
SS7 messages their networks to ensure that no rogue messages
appear
PSTN vs. VoIP
VoIP and SS7
GSM Network Elements
• Operators must be concerned about unauthorized access to
their Network Elements and their Operations Support
Systems.
• External access (e.g. through Internet or dialups) is a
concern but also Internal fraud such as modification of billing
records.
• Unfortunately, very few operators really audit security logs or
have capabilities to detect intrusions in their network.
• Network Intelligence is transferred from switches to UNIX
platforms, increasing their exposure to “traditional” security
issues.
GSM architecture
HLR – Home Location Register
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An unauthorized access to HLR could result in activating
subscribers not seen by the billing system, thus not chargeable.
Services may also be activated or deactivated for each subscriber,
thus allowing unauthorized access to services or denial of service
attacks.
In certain circumstances it is possible to use Man-Machine
Language (MML) commands to monitor other HLR user’s action this would also often allow for unauthorized access to data.
HLR – Home Location Register
• An operator should not rely on the fact that an intruder’s
knowledge on particular vendor’s MML language will be
limited. Those attacks can be performed both by external
intruders and by operator’s employees.
• Access control to HLRs should be based on user profiles,
using at least a unique username and a password as
authentication data.
• Remote access to HLR should be protected from
eavesdropping, source and destination spoofing and session
hijacking. An operator may therefore wish to limit the range of
protocols available for communication with HLR.
AuC: Authentication Center
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Number of employees having physical and logical access to AuC
should be limited. From security point of view it is then reasonable
to use an AuC which is not integrated with HLR.
Operators should carefully consider the need for encryption of AuC
data. Some vendors use default encryption, the algorithm being
proprietary and confidential. It should be noted that strength of
such encryption could be questionable.
If decided to use an add-on ciphering facility, attention should be
paid to cryptographic key management. Careless use of such
equipment could even lower AuC security.
Authentication triplets can be obtained from AuC by masquerading
as another system entity (namely HLR). The threat is present when
HLR and AuC are physically separated.
MSC: Mobile Switching Center
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An MSC is one of the most important nodes of any 3GPP network.
It handles all calls incoming to, or originating from subscribers
visiting the given switch area. Unauthorized, local or remote,
access to an MSC would likely result in the loss of confidentiality of
user data, unauthorized access to services or denial of service for
large numbers of subscribers.
It is strongly recommended that access to MSCs is restricted, both
in terms of physical and logical access. It is also recommended that
their physical location is not made public.
When co-located, several MSCs should be independent (i.e.
separated power, transmission,) in order to limit the impacts from
accidents on one particular MSC (e.g. fire).
CCBS: Customer Care and Billing System
• Unauthorized access to the billing or customer care system
could result in:
– loss of revenue due to manipulated CDRs (on the mediation
device/billing system level) .
– unauthorized applying of service discounts (customer care
system level), unauthorized access to services (false
subscriptions).
– and even denial of service - by repeated launching of resourceconsuming system jobs.
Value-Added Services
• Classic: VMS, SMS (MO, MT, Fleet, Broadcast, push / pull)
• Terminal-based: USSD, STK
• IN-based: Prepaid, VPN, Advanced screening and
forwarding, Universal number, …
• Internet: GPRS, WAP
• Location-based services
• Users increasingly want control over their communications
• Operators differentiate from competition with services, not
any more with coverage or tariffs
WAP Security Model
• Internet / SSL security affects the WAP security
• The WAP gateway ‘translates’ SSL messages into WTLS
for transmission over the air interface
The WAP gap
WTLS security
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Although the WTLS protocol is closely modeled on the well-studied
TLS protocol, a number of security problems have been identified
with WTLS:
– vulnerability to datagram truncation attack
– message forgery attack
– key-search shortcut for some exportable keys
WAP: no end-to-end trust
WAP: man-in-the-middle
Third Generation Wireless
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Evolution from existing European and US digital cellular systems
(W-CDMA, CDMA2000, UMTS).
Promises broadband multimedia on everyone’s handset and a
multitude of related services.
Spectrum up for auctions in many countries, put many operators in
financial debt.
Delays in 3G rollouts cast doubt over its success. Some talk about
jumping to 4G directly.
3G Security Architecture
3G Security Model
(IV)
User Application
Provider Application
(I)
(I)
(III)
USIM
HE
(II)
(I)
(I)
(I)
ME
AN
SN
Transport
stratum
Application
stratum
Home
stratum/
Serving
Stratum
3G Security Model
– Network access security (I): the set of security features that provide
users with secure access to 3G services, and which in particular
protect against attacks on the (radio) access link;
– Network domain security (II): the set of security features that enable
nodes in the provider domain to securely exchange signalling data, and
protect against attacks on the wireline network;
– User domain security (III): the set of security features that secure
access to mobile stations
– Application domain security (IV): the set of security features that
enable applications in the user and in the provider domain to securely
exchange messages.
– Visibility and configurability of security (V): the set of features that
enables the user to inform himself whether a security feature is in
operation or not and whether the use and provision of services should
depend on the security feature.
3G vs. GSM
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A change was made to defeat the false base station attack. The
security mechanisms include a sequence number that ensures that
the mobile can identify the network.
Key lengths were increased to allow for the possibility of stronger
algorithms for encryption and integrity.
Mechanisms were included to support security within and between
networks.
Security is based within the switch rather than the base station as
in GSM. Therefore links are protected between the base station
and switch.
Integrity mechanisms for the terminal identity (IMEI) have been
designed in from the start, rather than that introduced late into
GSM.
3G vs. GSM
• GSM authentication vector: temporary authentication data
that enables an VLR/SGSN to engage in GSM AKA with a
particular user. A triplet consists of three elements: a) a
network challenge RAND, b) an expected user response
SRES and c) a cipher key Kc.
• UMTS authentication vector: temporary authentication data
that enables an VLR/SGSN to engage in UMTS AKA with a
particular user. A quintet consists of five elements: a) a
network challenge RAND, b) an expected user response
XRES, c) a cipher key CK, d) an integrity key IK and e) a
network authentication token AUTN.
AKA Message Flow
Connection Establishment Overview
Ciphering and Integrity
Interception
• CDR data always available to authorities, kept forever in
operators’ data warehouses GSM monitoring facilities
designed as an “after thought”.
• System plugs onto MSC special interface and allows
interception of signalling and speech traffic.
• Monitoring and interception can be delocalized from the MSC
• 3G has done a much better job for big brother.
• Any event can be intercepted in a very user-friendly way
• Billing data can be intercepted in real-time.
Interception: terminology
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Network Based Interception: Interception that is invoked at a
network access point regardless of Target Identity.
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Subject Based Interception: Interception that is invoked using a
specific Target Identity
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Target Identity: A technical identity that uniquely identifies a target
of interception. One target may have one or several identities.
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Interception Area: Subset of the network service area comprised
of a set of cells which defines a geographical zone.
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Location Dependent Interception: Interception of a target mobile
within a network service area that is restricted to one or several
Interception Areas (IA).
Interception: Definitions
• ADMF: Administrative Function
– interfaces with all the LEAs that may require interception in the
intercepting network
– keeps the intercept activities of individual LEAs separate
– interfaces to the intercepting network
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LEA: Law Enforcement Agency
HI2: Distributes Intercept Related Information (IRI) to LEA
HI3: Distributes Content of Communication (CC) to LEA
PDP: Packet Data Protocol
Logical configuration
HI1
X1_1
Mediation
Function
ADMF
X1_2
LEMF
LEMF
X1_3
HI2
X2
Mediation
Function
LEMF
Deliv ery
Function 2
HI3
X3
Mediation
Function
Deliv ery
Function 3
3G MSC,
3G GSN
Interception: Concepts
• The target identities for interception can be at least on of the
following: IMSI, MSISDN or IMEI.
• The interception request is sent from the ADMF to the 3G
MSC and 3G GSN (X1_1-interface) and specify
– target identities (MSISDN, IMSI or IMEI)
– information whether the Content of Communication shall be provided
– information whether the Intercept Related Information shall be
provided
– address of Delivery Function 2 for the IRI
– address of Delivery Function 3 for the intercepted CC
– IA in case of location dependent interception.
Circuit Event Records
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•
•
•
•
•
•
•
Observed MSISDN, IMSI or IMEI
Event type (Establishment, Answer, Supplementary service,
Handover, Release, SMS, Location update, Subscriber controlled
input )
Dialled #, connected #, other party address, forwarded #
Cell ID, Location Area Code
Basic service, supplementary services
SMS message (content and header)
Redirecting number (the number which invokes the call forwarding
towards the target)
SCI (Non call related Subscriber Controlled Input which the 3G
MSC receives from the ME)
Packet Data Event Records
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•
•
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Observed MSISDN, IMSI, IMEI
Event type (PDP attach, PDP detach, PDP context activation, PDP
context deactivation, SMS, Cell and/or RA update)
PDP address, PDP type
Access Point Name, Routing Area Code
SMS (content and header, including SMSC centre address)
Cell Global Identity
Interception Security
– It shall be possible to configure the authorised user access
within the serving network to Activate, Deactivate and
Interrogate Lawful Interception separately for every physical or
logical port at the 3G MSC and DF. It shall be possible to
password protect user access.
– Only the ADMF is allowed to have access to the LI functionality
in the 3G MSC, 3G GSN and DF.
– The communication links between ADMF, 3G GSN, 3G MSC
and the various delivery functions may be required by national
option to support security mechanisms, such as CUG, VPN,
etc.
Thanks
[email protected]
References
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3rd Generation Partnership Project; A guide to 3rd generation security, Technical Specification Group and
System Aspects
3rd Generation Partnership Project; Lawful Interception Architecture and Functions, Technical Specification
Group Services and System Aspects
On the security of 3GPP networks, Michael Walker, Vodafone Airtouch & Royal Holloway, University of
London
Closing the gap in WAP, Cylink Corporation